1. Field of the Invention
The present invention relates to a sheet-shaped medium processing apparatus, an image forming apparatus and a sheet-shaped medium after-treatment apparatus.
2. Description of the Prior Art
In the sheet-shaped medium after-treatment apparatus and the image forming apparatus, which conduct after-treatment such as punch unit treatment of puncturing punch hole for filing on papers discharged from the image forming apparatus after image formation, staple treatment by using staple means, sealing treatment of a seal and so forth, the papers discharged from discharging means thereof are taken in on sheet piling means (hereinafter referred to as a tray). The piled papers are subjected to automatic arrangement for the sake of exploitation thereafter, however, degree of paper arrangement namely degree of precision of arrangement becomes problem.
In FIG. 25, which indicates one example of a conventional paper processing apparatus, sheet-shaped medium (hereinafter referred to as papers) S that is sent toward the paper processing apparatus along conveyance direction A after being subjected to image formation by using an image forming apparatus that is not illustrated, is introduced to one pair of paper discharge roller 3 as discharging means via a discharging sensor for detecting passage of the paper. A tray 12′ is located in down below of the paper discharge roller 3. The paper S, which is discharged in the discharge direction “a” (direction at right angle to an axis line of the paper discharge roller 3 in approximate horizontal plane) to be prolongation of the conveyance direction from the paper discharge roller 3, falls toward obliquely downward falling direction B depending on inertia and own weight after rear end portion of the paper S leaves from the paper discharge roller 3, then the paper is piled on a shift tray 12′.
When there is no paper on the shift tray 12′, the paper lands with free fall distance from upper surface of the shift tray 12′ to a nip section of the paper discharge roller 3, while when the paper S is piled on surface of the shift tray 12′, the paper lands with free fall distance L from the top surface of the piled paper S to the nip section.
Meanwhile, the paper processing apparatus possesses sorting function, in order to achieve this sorting function, the shift tray 12′ is capable of reciprocating with predetermined amount of stroke (shift amount) necessary for the sorting in a shift direction “c” at right angle to the discharge direction “a” in the horizontal plane. The shift tray 12′ capable of being slid, which is hold at a pedestal 4 extending in the shift direction “c”, is made to reciprocate in the shift direction “c” on the pedestal 4 by using drive mechanism that is not illustrated, at the time of sorting.
Outline of sorting action is that the papers of predetermined number of sorting are piled on the shift tray 12′ of being at a halt in one end of reciprocating of movement stroke of the reciprocating. For instance, in cases where several copies of the paper sheaf with 8 sheets of papers as a copy are made to sort to be piled, {circle around (1)} at the time that the shift tray 12′ is located at one end of reciprocation, 8 sheets of papers are discharged to be piled continuously on the shift tray 12′ from the paper discharge roller 3 sequentially. {circle around (2)} next, the shift tray 12′ moves to the other end of the reciprocation, when the shift tray 12′ is located at the other end of the reciprocation, the papers S are discharged to be piled thereon from the paper discharge roller 3. {circle around (3)} After 8 sheets of papers are piled on the shift tray 12′ at the other end of the reciprocation, the shift tray 12′ moves to the one end of the reciprocation, and the same operation as the above {circle around (1)} is conducted.
And under, the same action is repeated until the paper sheaf corresponding to required number of copies are piled. As a result, on the shift tray 12′, it is possible to obtain piled state that is one in which required copies of paper sheaf are sorted in such a way that steps of paper end surface between respective copies are sorted by concave-convex shaped steps corresponding to shift amount of the shift tray 12′ with the paper sheaf of 8-sheet-one-set as one copy.
{circle around (1)} However, in order to reciprocate the shift tray 12′ in the shift direction “c” described above, it is necessary to provide drive means, as the drive means, for instance, a concave-convex-shaped section is formed at the rear end portion of the shift tray 12′, and a concave-convex shaped section fitted into the above described concave-convex shaped section at an end-fence to be rear end receive portion of the paper, in which these respective concave-convex shaped sections are made gearing conditions, further, an eccentric pin is made to engage into a hole extended in the radius direction formed at part of the end-fence, and the eccentric pin is made to rotate by a motor.
At this case, it is possible to obtain necessary shift amount for the sorting in accordance with amount of eccentricity of the eccentric pin, however, since power to operate is different depending on the number of the paper (weight) piled on the shift tray 12′, it is necessary to consider drive motor power of the tray, and the other mechanical parts on condition that maximum possible number of papers are piled, so, in the case of shift action for small number of the paper, it is impossible to use full power of the drive motor, resulting in design with low efficiency.
{circle around (2)} In addition, in FIG. 25, the paper S discharged from the paper discharge roller 3 is simply piled on the shift tray 12′ through being subjected to free fall within the space of free fall distance L. Namely, the paper S of departing from the paper discharge roller 3 is under free condition until the paper S is piled on the shift tray 12′, so, lateral resist of the paper S received from the image forming apparatus is off to the side, or the paper is twisted with skew, so that paper end face in the shift direction “c” of the paper of being piled on the shift tray 12′ does not line up among the papers resulting in occurrence of paper irregularity with lateral gap amount Δ.
Copy agency and so forth require pile with sorting condition of extremely precision because paper sheaves assorted to be piled are treated at next process, for instance the paper sheaves are treated by punch unit. If the paper sheaves are in sorting condition with bad precision, since punch unit processing should be conducted after the paper sheaves taken out from the shift tray 12′ are made to arrange again by hands, so that waste occurs at the point of working efficiency. For that reason, copy agency and so forth require severe arrangement precision about piled paper, so improvement of arrangement precision is desired.
{circle around (3)} Followings are this kind of known technique.                (a) Official gazette of Japanese Patent Laid-Open No. HEI 10-245148 discloses technique in which there is provided two aligning members capable of moving independently at both sides of width direction at right angles to sheet transfer direction, and these aligning members execute two processing actions of sheet arranging processing in the width direction and shift processing of sorting the sheet in every number of copy, however, since the aligning member conducts two kinds of processing of the sheet arranging processing and the shift processing, mechanism is complicated.        (b) Official gazette of Japanese Patent Laid-Open No. HEI 5-286609 discloses technique in which sheet is discharged on a carriage capable of moving in a direction of traversing sheet discharge direction, and position of the sheet is aligned in such a way as to move the carriage until the sheet on the carriage is detected by a sensor, however, it is difficult to say that the technique is suitable for alignment of mutual piled many sheets.        (c) Official gazette of the patent (U.S. Pat. No. 2,761,221) discloses technique for aligning transfer paper on the paper discharge tray by use of jogger fence to be aligning means, however, since the technique is one for aligning the transfer paper on the paper discharge tray, it is impossible to conduct sorting.        (d) Official gazette of Japanese Utility Model Laid-Open No. HEI 5-10367 discloses technique in which there are provided two paper discharge side fences of standing upright oppositely on the paper discharge tray, and the paper is piled therebetween, so, respective insides of these side fences, there are provided guide sections capable of projecting and being evacuated, in which the paper discharged between side fences is made to curve by use of the guide sections under projected condition, thereafter, the paper is subjected to free-fall on the paper discharge tray with the guide sections evacuated, however, it is impossible to sort the paper.        